Divert-air valves for recirculation of condensed fresh gas, optionally with recirculated exhaust gas, from the pressure side of a compressor of a turbocharger back to the suction side of the compressor, have previously been described. The connection between the pressure side and the suction side of the compressor via a bypass line is required for the transition from a high load into the coasting operation of the internal combustion engine to prevent a high conveyance of the booster pump against a closed throttle flap, to prevent the resultant pumping effect, and to prevent a sudden drop of the turbo speed which is too strong with resulting thermodynamic problems.
Divert-air valves are frequently operated electromagnetically with the valve closure body of the valve being moved via the armature by an electromagnetic force. An example of such an arrangement is described in DE 100 20 041 A1. Control is performed via a control unit in accordance with correspondingly existing motor data. The valve comprises a pressure compensation opening on the valve closure body whereby a balance of forces is established for the pneumatic forces with a corresponding design of the effective surfaces. The closure body in this valve is connected directly to the armature, and the interior of the valve is separated from the outer region via a membrane. A bore is formed in the armature and the closure body via which a pressure compensation is established between the pressure side of the turbo charger and the interior of the valve.
A valve was normally omitted in subsequent generations of divert-air valves. A substantially cylindrical control body was used which was connected in a gimbaled manner to the armature, and which in the radially outer region was sealed by a sealing ring instead a membrane. Such a divert-air valve is described, for example, in DE 10 2010 026 121 A1. The substantially cylindrical control body comprises, at its end facing toward the armature, a constriction which has a widened portion of a sliding sleeve gripping behind it which is connected to the armature so that the armature together with the sliding sleeve and the control body will be lifted off or lowered onto the valve seat.
Other publications, such as WO 2014/102133 A1 or DE 10 2004 044 439 B4, describe a constriction directly at the armature followed by a widened portion so that the control body, after having been inserted via the widened portion, will grip into the constriction and thus be fastened in a form-locking manner. The control body must be provided with radially inward facing, resilient elements therefor. The control body therefor is normally produced as a plastic part which, however, only has limited thermal resistance.
The ends of these control bodies which face toward the valve seat consist of the axial ends of their cylindrical outer surface. These arrangements therefore have the disadvantage that new shapes for the control bodies must be designed in each case for turbo chargers generating different pressures, while the diameters of these shapes must be adapted to the cross sections that are to be sealed. These arrangements are further often not suited for increased operating temperatures due to the plastic material used. Problems also occur via closing and opening movements which are too noisy. Problems may in particular occur with respect to sealing tightness.